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Introduction In recent years, Cobalt has been used as a component in metal-on-metal (MoM) bearings for orthopaedic knee and hip replacements, due to abnormal wear and corrosion they can result in the release of cobalt ions (Co2+). Chronic cobalt exposure has been shown to cause cardiac contractile dysfunction, but the cellular mechanisms underlying these cardiotoxic effects are not completely understood. This study aims to investigate the acute effects of cobalt on cardiomyocytes, focusing on calcium handling and its impact on the oxidation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). Methods Male Sprague Dawley rat hearts were perfused with collagenase type I and protease, in order to isolate cardiac myocytes. Isolated cardiomyocytes were exposed to various CoCl2 concentrations, including control (no cobalt), 1μM, 10μM, and 100μM, for 5 min and 1 h. To measure cellular Ca2+, cells were leaded with Cal520 AM for 20 mins. A spinning disk confocal microscope was used to measure calcium at 200Hz. Myocytes were electrically paced at 1Hz at room temperature and the effects of cobalt on cardiomyocyte Ca2+ transient amplitude, Ca2+ spark amplitude, and Ca2+ spark frequency were assessed. Furthermore, western blotting was employed to quantify the expression of oxidated-CAMKII in isolated cardiomyocytes. Results Calcium transients refer to the increase and subsequent decrease in global intracellular calcium concentration that occurs during each heartbeat. Ca2+ transient amplitude in cardiac myocytes were significantly reduced following exposure to 10μM of Cobalt for 5 minutes as well as 1 hour of 1μM and 10μM of cobalt when compared with control (p Conclusions This study demonstrates that acute cobalt exposure in cardiomyocytes results in calcium handling dysregulation; however, there is not enough evidence to confirm that this occurs due to CaMKII activation. Further research is necessary to further understand the underlying mechanisms of action of cobalt on these cells. Conflict of Interest None
Ruiz et al. (Mon,) studied this question.